Torpedo antiself homing(ash)system

ABSTRACT

A system to prevent a torpedo from attacking the launch vessel. Whenever the torpedo heading deviates by more than a predetermined angle from the base runout course a gyro provides a contact closure. The torpedo also supplies incremental range information representing a known distance of torpedo travel, which in conjunction with the contact closure, supplies a shutdown command to stop the torpedo propulsion system.

United States Patent [191 [111 3,826,216

Timberlake July 30, 1974 TORPEDO ANTISELF HOMING(ASH)SYSTEM Primary ExaminerBenjamin A. Borchelt I Assistant Examiner-Thomas H. Webb [75] Inventor g Tlmberlake Sflver Spring Attorney, Agent, or Firm--R. S. Sciascia; J. A. Cooke;

W. W. Cochran [73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC. ABSTRACT [22] Filed: May 21, 1973 A system to prevent a torpedo from attacking the launch vessel. Whenever the torpedo heading deviates [21] Appl' 362614 by more than a predetermined angle from the base runout course a gyro provides a contact closure. The [52] U.S. Cl 114/24, 114/20 torpedo also supplies incremental range information F421) F42b b 9/ 0 representing a known distance of torpedo travel, [58] Field Of Search 114/20, 21, 24 which in conjunction with the contact closure, supplies a shutdown command to stop the torpedo [56] References Cited propulsion system.

UNITED STATES PATENTS 6 Cl 2 D 3,033,148 5/1962 Cooke 114/21 R ACR 75 CONTACT SIGNAL GYRO INCREMENTAL RANGE INFORMATION GENERATOR EYl mox R.C.= MAXIMUM RANGE OF CONCERN min E. R. MAXIMUM ENABLE RANGE PAIENTEII 3,826,210

suwaor 2 MIN. ENABLE RANGE MAX. RANGE OF CONCERN I l I CASEI I l I I k RANGE 2A 1 0/ CASE 2 I I r -RANGE A--fl I RANGE 2A -*w d/ CASE 3 B+C=A I I I L I SHUTDOWN: I I f I I of CASE 4i TORPEDO TRACK ALONG BASE COURSE KEY! O LAUNCH POINT FIRST TURNAROUND POINT X ASH SHUTDOWN POINT TORPEDO ANTISELF HOMING(ASH)SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to torpedo guidance systems and more specifically to antihoming control systems. Basically two methods are known to the prior art to prevent homing torpedos from attacking their launch vessels.

The Anticircular Run (ACR) method is intended to prevent torpedos having erratic trajectories from accidentally impacting their launch vessels shortly after launch. Under this method, if torpedo turns back or tends to circle in azimuth before running out a specified distance, its propulsion system will be disenabled and its warhead dudded or made safe in some analogous manner. The launch vessel, however, is usually within the homing range of the torpedo after it has runout this specified distance. The ACR method thus is ineffective to stop the torpedo from homing in on the launch vessel once it has initially run out the specified distance.

The Stratum method protects the launch vessel by specifying depth ranges for torpedo attack before launch. The torpedo is allowed to home in on any target above a specified floor and below a specified ceiling depth. As long as the launch vessel stays above the ceiling depth or below the floor depth it will not be hit by the torpedo even if it is acquired by the torpedo homing system. However to use Stratum protection to prevent a homing torpedo from attacking the launch vessel, the depth of the enemy target submarine must be known so that appropriate ceiling and floor limits can be established before the torpedo is launched. Because of acoustic ray bending and sonar limitations this is not always known. Also, this method of protection cannot be used if the target is at the same depth as the launch vessel. In addition, a target submarine which moves to a Stratum-protected depth after the torpedo is launched is also safe from attack. In either case, a safe depth for a launch submarine is also a safe depth for the target submarine and the torpedo employing Stratum protection is ineffective. Clearly this method is ineffective for a surface launch against a surfaced target since the surface launch vessel is in the same stratum as the surface target.

SUMMARY OF THE INVENTION The present invention provides a system which effectively prevents torpedo self homing. An up-down counter accumulates pulses representative of distance travelled by the torpedo through the up portion of the counter while the torpedo is travelling in a direction having an angle, as measured from the torpedo base course, which is less than a predetermined angle. If the direction of the torpedo is such that the predetermined angle is exceeded, a gyroscope enables gating circuitry to gate the distance pulses to the down portion of the up-down counter. In addition, a divide-by-two circuit is included in the up channel of the counter so that pulses are accumulated twice as fast in the down portion. If the accumulated pulses in the up-down counter ever become less than some minimum value representative of a minimum enable range, while the predetermined angle is exceeded, a shutdown signal is generated by further gating circuitry. Also included in the device is a latch circuit which is set when the count in the updown counter reaches some maximum value representing a distance from the launch vehicle greater than the maximum acquisition range of the torpedo. After the latch circuit is set the homing mechanism of the torpedo operates without interference from ASH system.

It is therefore an object of the present invention to prevent a torpedo from attacking targets in the vicinity of the launch vessel.

It is also the object of the present invention to provide an antiself homing torpedo protection system which can be used as an alternative to a stratum protection system.

It is another object of the invention to provide an antiself homing torpedo protection system which can be used in conjunction with a stratum protection system.

Another object of the invention is to provide a torpedo protection system in which the depth of the enemy target need not be known.

Still another object of the invention is to provide a torpedo protection system which can be used against targets at the same stratum level of the launch vessel.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows the circuitry of the preferred embodiment.

FIG. 2 is a diagram of a series of shutdown situations provided by the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A block diagram of the circuitry of the antiself homing (ASH) system is shown in FIG. 1. A gyroscope 10 which was developed as part of the anticircular run system is used in the present device to provide a contact closure whenever the tropedo heading deviates from the base runout course by more than a specified angle, for example, The contact closure is inhibited after launch just long enough for the torpedo to turn to this base course from its launch heading. The torpedo also supplies incremental range information to the ASH System via input 26. This information is in the form of a series of pulses with a rate proportional to the torpedo propulsion shaft speed. The output pulses are obtained from an alternator which is driven from the tropedo propulsion shaft through a gear train to supply electrical power for the torpedo. Each pulse thereby represents a known distance which the torpedo has traveled.

The up-down counter 20 of FIG. 1 is designed to produce an output to the second latch circuit 22 when a specified number of incremental range pulses have been accumulated in the counter 20 through the +2 circuit 18 and the up input to represent a maximum range of concern as shown in FIG. 2. If this occurs, the second latch circuit 22 prevents shutdown and the torpedo is allowed to search and home in any direction and will not be interruptd by the ASH System. The maximum range of concern is chosen to be greater than the maximum acquisition range of the torpedo homing system for extreme conditions so that there is no chance of homing on the launch vessel.

The i 75 contact on the ACR gyro will close when the torpedo turns off of the base course heading enough that it could be homing on the launch vessel or running back toward the launch point. If this occurs, the incremental range pulses are gated into the down input of the counter 20 via and gate 16. Because the +2 circuit 18 is not ahead of this input, the counter value indicating accumulated range from the launch point will be decremented twice as fast as it was inremented for the same torpedo speed. When the counter value is below the minimum enable range and the ACR gyro :75" contact is closed, a shutdown command is generated which stops the torpedo propulsion system and renders the torpedo safe provided latch 22 has not been set by the up-down counter 20 to inhibit shutdown.

The operation of the ASH shutdown system is diagrammatically shown in FIG. 2. In case 1, the torpedo attempts to turn off its base course before it has run out to the minimum enable range. This causes the ACR gyro 10 to produce a contact signal which enables and gate 24 to produce a shutdown signal since signals are present at the output 30 of the counter and output 28 of latch 22.

In case 2, the ASH System will allow the torpedo to run straight out past the minimum enable range until turnaround is detected, and then straight back half way to the minimum enable range before shutdown is commanded.

In case 3, before the minimum enable range is reached, the ACR :75" contact opens indicating that the torpedo has turned further and is again running away from the launch point. Accordingly, the imcremental range pulses are inhibited from reaching the down input of the counter and the value stored in the counter at that time remains constant until the ACR gyro 175 contacts are again closed indicating that the torpedo was once again started heading back toward the launch point. At this time the counter again begins to decrement and upon reaching a representation of less than the minimum enable range causes the shutdown command to be generated. This action of stopping and starting the decrementing of the counter as the torpedo turns away from and back towards the launch point results in the shutdown command which is generated farther than half way back to the Minimum enable Range from the first turnaround point as shown in case 3, FIG. 3. The ASH System allows the launch vessel some maneuvering flexibility after launch even though the torpedo may take a zigzag course away from the launch point, i.e., within the i75 ACR Gyro contact limits, and take a straight line course back toward the launch point which is not possible in the ACR systems. In addition the launch vessel is able to continue to move in the same direction as the torpedo after launch without danger of being attacked by its own torpedo as long as the speed of the launch vessel is much less than the speed of the torpedo.

A clear advantage of the ASH system over the previously used stratrum (depth separation) system is that the ASH system can be used in many tactical situations where depth separation cannot be used because of the target depth uncertainty and mobility. The ASH system limits the freedom of the torpedo to home in the azimuthal plane which the Stratum system does not do.

The ASH system and Stratum Limitation could be used together to provide the maximum tactical flexibility and the maximum protection to the launch vessel.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. For example, the latch circuit 12 could be replaced by a simple inverter. In this configuration, the counter would be incremented by the range pulses should the torpedo turn and run away from the launch point after once having turned back toward the launch point. Thus, the altered ASH system will command shutdown when the total distance traveled back toward the launch point is half of the total distance traveled from the minimum enabled range in a direction away from the launch point. Another alternative to the ASH system herein described is obtained by changing the +2 circuit 18 shown in FIG. 1 to a circuit that divides by another quantity equal to or greater than I. This results in a different ratio of run-out to run-back distance. Also, the angle about the base course at which the ACR Gyro contacts close may be varied. The angular limits must be wide enough to allow for gyro drift and control system deviations to occur and for a certain amount of zigzag course to be followed for searching. An angle greater than however, would allow the torpedo to work its way back toward the launch point without decrementing the up-down counter and would be too large to allow the ASH system to be very effective. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically claimed herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A torpedo control system for preventing a homing torpedo from attacking targets in the vicinity of its launch vessel comprising:

means for generating a signal if said torpedo has changed direction by more than a predetermined angle;

means for generating pulses representative of the range traveled by said torpedo;

pulse counter means having incrementing and decrementing inputs and a first output for producing a signal upon accumulating a predetermined maximum number of said pulses and a second output for producing a signal until a predetermined minimum number of said pulses is accumulated;

first semiconductor gating means controlled by said direction change signal generating means for applying said pulses representative of range to one of said inputs of said counter means;

second semiconductor gating means for producing a torpedo shutdown control upon the occurrence of signals from said first output and said signal generating means.

2. The control system of claim 1 wherein said first gating means comprises:

inverting means connected to said signal generating means for producing a signal only when a signal is not present at its input;

third gating means connected to said inverting means and said means for generating pulses for gating said pulses representative of range to said incrementing input of said pulse counter means only when a signal is produced by said inverting means;

fourth gating means connected to said direction change signal generating means and said means for generating pulses for gating said pulses representaadditional inverting means connected to said first tive of range to said decrementing input of said input of said counter means for producing a signal counting means only when a signal is produced by only when a signal is not present at its input; said signal generating means. an and gate connected to the output of said invert- 3. The control system of claim 2 wherein said invert- 5 ing means and said second output of said counter ing means comprises a latch circuit. means and said signal generating means for pro- 4. The control system of claim 1 wherein said second ducing a shutdown control. gating means comprises: 6. The control system of claim 3 wherein said second inverting means connected to said first output of said gating means comprises:

counter means for producing a signal only when a 10 additional inverting means connected to said first signal is not present at its input; output of said counter means for producing a signal an and gate connected to the output of said invertonly when a signal is not present at its input;

ing means and said second output of said counter an and gate connected to the output of said invertmeans and said signal generating means for proing means and said second output of said counter ducing a shutdown control. 5 means and said signal generating means for pro- 5. The control system of claim 2 wherein said second ducing a shutdown control. gating means comprises: 

1. A torpedo control system for preventing a homing torpedo from attacking targets in the vicinity of its launch vessel comprising: means for generating a signal if said torpedo has changed direction by more than a predetermined angle; means for generating pulses representative of the range traveled by said torpedo; pulse counter means having incrementing and decrementing inputs and a first output for producing a signal upon accumulating a predetermined maximum number of said pulses and a second output for producing a signal until a predetermined minimum number of said pulses is accumulated; first semiconductor gating means controlled by said direction change signal generating means for applying said pulses representative of range to one of said inputs of said counter means; second semiconductor gating means for producing a torpedo shutdown control upon the occurrence of signals from said first output and said signal generating means.
 2. The control system of claim 1 wherein said first gating means comprises: inverting means connected to said signal generating means for producing a signal only when a signal is not present at its input; third gating means connected to said inverting means and said means for generating pulses for gating said pulses representative of range to said incrementing input of said pulse counter means only when a signal is produced by said inverting means; fourth gating means connected to said direction change signal generating means and said means for generating pulses for gating said pulses representative of range to said decrementing input of said counting means only when a signal is produced by said signal generating means.
 3. The control system of claim 2 wherein said inverting means comprises a latch circuit.
 4. The control system of claim 1 wherein said second gating means comprises: inverting means connected to said first output of said counter means for producing a signal only when a signal is not present at its input; an ''''and'''' gate connected to the output of said inverting means and said second output of said counter means and said signal generating means for producing a shutdown control.
 5. The control system of claim 2 wherein said second gating means comprises: additional inverting means connected to said first input of said counter means for producing a signal only when a signal is not present at its input; an ''''and'''' gate connected to the output of said inverting means and said second output of said counter means and said signal generating means for producing a shutdown control.
 6. The control system of claim 3 wherein said second gating means comprises: additional inverting means connected to said first output of said counter means for producing a signal only when a signal is not present at its input; an ''''and'''' gate connected to the output of said inverting means and said second output of said counter means and said signal generating means for producing a shutdown control. 